Filter form list values

I have an API with filtering support using RSQL, having an endpoint GET /movies?filter=genre==Music;rating==TV-14;language==es

In order for the web app to populate the dropdowns in the filtering form it needs to make independent request to /genres, /ratings and /languages.

I am wondering what could be a solution to defined a REST Resource for returning these 3 lists in a single request. Does this goes against REST?

Thank you in advance for any recomendation

I’m not completely sure if you are in the right forum here because your api does not look like JSON:API.

However you can perform a single request via JSON:API to get all informations you need regardless of the number of independent resources. You just need to include them.

GET /movies?include=genres,ratings,languages